Responses to 3600 IU Vitamin D or Calcifediol – Oct 2022

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Evaluation of 14-day Concentration-time Curves of Vitamin D3 and 25-Hydroxyvitamin D3 in Healthy Adults With Varying Body Mass Index

Anticancer Research 42: 5095-5100 (2022) doi: 10.21873/anticanres .16019
NIPITH CHAROENNGAM1’2’3, PETER M. MUELLER4 and MICHAEL F. HOLICK1
department of Medicine, Section of Endocrinology, Nutrition, and Diabetes, Vitamin D,
1 Skin and Bone Research Laboratory, Boston University Medical Center, Boston, MA, U.S.A.;
2 Department of Medicine, Mount Auburn Hospital, Harvard Medical School, Cambridge, MA, U.S.A.;
3 Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand;
4 Carbogen Amcis AG, Bubendorf, Switzerland

Background/Aim: To analyze the concentration-time curves of single-dose oral 25(OH)D3 in comparison with vitamin D3 in healthy adults.
Patients and Methods: The pharmacokinetics observed over two weeks after orally administering single 900 fig doses of vitamin D3 and 25( OH)D3 to six otherwise healthy vitamin D insufficient/deficient adults participating in a broader randomized, double-blind, crossover, single center trial was analyzed. The study protocol was approved by the institutional review board (H-37167).

Results: Individual concentration-time curves revealed that vitamin D3 took longer than 25(OH)D3 to reach its maximal concentration after ingestion in five participants. After 25(OH)D3 ingestion, 25(OH)D3 reached its maximal concentration, dropped rapidly, and plateaued before starting to decrease slowly. There were observable inter-individual variations in the bioavailability of vitamin D3 and 25(OH)D3 and the pattern of changes in 25(OH)D3 concentration after their ingestion.
Conclusion: Pharmacokinetics of 25(OH)D3 in comparison with vitamin D3 was illustrated and described in this study.
 Download the 2022 PDF from VitaminDWiki

2022 PDF conclusion

We reported the concentration-time curves of orally administered single dose of 900 |ag vitamin D3 and 25(OH)D3 in healthy adults.
We found that oral 25(OH)D3

• was absorbed faster,
• stayed longer in the circulation, and
• caused a more rapid increase in serum 25(OH)D3 than oral vitamin D3.

These results imply that 25(OH)D is absorbed via the enterohepatic system unlike vitamin D that is absorbed via lymphatic system. Therefore, oral 25(OH)D may be a useful choice of treatment in conditions that benefit from rapid correction of vitamin D deficiency such as symptomatic osteomalacia, hypocalcemia, or proximal muscle weakness due to severe vitamin D deficiency. In the concentration-time curves of 25(OH)D3, there is a somewhattext delayed increase in serum 25(OH)D3 level after its rapid peak, which may represent tissue re-equilibration of 25(OH)D3. Finally, wetext observed some inter-individual difference in the bioavailability of 25(OH)D3 in participants with otherwise similar bioavailability of vitamin D3.

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2022 study says vitamin D uses the lymph system, yet the intestinal lymph trunk transit time to Thoracic node is 1 day

• "Vitamin D is a non-polar and highly lipophilic substance that is easily incorporated into lipid bilayers. Due to its lipophilic character, the gastrointestinal absorption of vitamin D takes place predominantly via the lymphatic pathway."
• "These results imply that 25(OH)D is absorbed via the enterohepatic system unlike vitamin D that is absorbed via lymphatic system"
  • No references for either assertion

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Their 2021 pilot study: All 18 had <30 ng, 37% had malabsorption, (but only 6 subjects were in the 2022 study - which were dropped?)

• Did the 2022 study drop those with High BMI, those with Malabsorptoon, or what?

A pilot-randomized, double-blind crossover trial to evaluate the pharmacokinetics of orally administered 25-hydroxyvitamin D3 and vitamin D3 in healthy adults with differing BMI and in adults with intestinal malabsorption

Vitamin D does not appear to have a half life

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Vitamin D peak was only 5 hours behind the Calcifediol peak

 Download the 2021 PDF from VitaminDWiki

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VitaminDWiki - Calcidiol category contains

46 items in Calcidiol category

Calcidiol = Calcifediol = 25-hydroxyvitamin D3 = 25(OH)D = semi-activated Vitamin D
See also

• Calcifediol (Calcidiol, semiactivated Vitamin D) - many studies 55 as of Jan 2024
• Tests for Vitamin D 156 items
• Calcitriol 56 items
• Injection 62 items
• Forms of Vitamin D 107 items
• Response to Vitamin D - many studies 166 as of April 2023
• Nanoemulsion Vitamin D is faster and better - many studies
  • Response to Nanoemulstion Vitamin D swished in the mouth appears to start in 2 hours
• Calcidiol is available only by prescription and is expensive
• Calcidiol - daily dose has fast response, but weekly might be better - March 2018